1. Field of the Invention
The present invention relates to fuel additives, fuels, and to methods of making and using same. In another aspect, the present invention relatives to low sulfur fuel additives, low sulfur fuels, and to methods of making and using same. In even another aspect, the present invention relates to fuel additives having 15 ppm sulfur at most, fuels having 15 ppm sulfur at most, and to methods of making and using same.
2. Background
Economic and environmental considerations are creating great market demand for renewable sources of raw materials, such as those utilized in the transportation industry. Examples include the fuel and fuel package market. Specifically, environmental concerns have led to regulatory mandates requiring sulfur levels to be reduced in fuels. However, low sulfur fuels are known to be less lubricating they are typically treated with lubricity additives. However, fuel additives, including lubricity additives, are also subject to regulatory standards relating to reduced sulfur levels. Specifically, U.S. regulations require that most fuel additives contain no more than 15 ppm sulfur.
The fuel industry in the United States has been attempting to meet these regulatory mandates that require the use of fully formulated ultra low sulfur diesel fuels (ULSD) with a maximum of 15 ppm sulfur content. The requirement is quite stringent requiring not only the final produced fuel, but also requiring that each component going into such fuels have a sulfur content of 15 ppm maximum.
As an additional requirement, many fuel compositions and fuel additives, including lubricity additives, are stored in outdoor tanks and therefore need to remain liquid and at a low viscosity even at low temperatures. Many commonly known lubricity additives, despite having excellent lubricating properties, do not remain free of crystals at low temperatures.
Tall oil fatty acids (TOFAs) are considered valuable for use in various applications due to their good lubricating properties. Tall oil is a by-product in the manufacture of paper pulp by digestion of wood with alkaline solutions of sodium sulfide. Tall oil fatty acids may be isolated from the tall oil using various processing techniques. However, sulfur species are introduced into tall oil products during the Kraft process, which includes the addition of sodium sulfide and sodium hydroxide to wood chips for digestion, and then the neutralization/acidification of the basic mixture with sulfuric acid. Both of these processes can generate sulfur species, both organic and/or inorganic, which are carried along with black liquor soap, and then into the crude tall oil (CTO). Further refinement through fractional distillation of the CTO generally concentrates the sulfur species into specific product streams (pitch, rosin, and heads); however it does not eliminate the sulfur species from TOFA.
Thus, tall oil fatty acids often contain undesirably high levels of sulfur that is introduced during the pulping process. Furthermore, tall oil fatty acids, even when greatly diluted in solvent, typically do not remain free of crystals at low temperatures.
TOFA is separated from other tall oil components through distillation; however, during the distillation process unsaponifiable and sulfurized materials tend to co-distill with TOFA. Additional distillation to purify tall oil fatty acid further, increase cost of production; in addition additional distillation may produce materials with more than the desired amount of rosin acid and unsaponifiable tall oil species in the final tall oil fatty acid.
High sulfur content in tall oil products, not only hinders its use as fuel additives in fuels it also impacts the usefulness of tall oil products in other, useful value-added chemistries. For example, sulfur content can inhibit the hydrogenolvsis of tall oil products into alcohols. Another example is the hydrogenation of dimer acids as well as monomer. Sulfur species in conventional tall oil can contaminate hydrogenation catalysts, thus “killing” or “poisoning” the catalyst and making the conversion of such conventional tall oil products very economically inefficient and undesirable. Thus, there exists a need to create tall oil products from renewable resources in a manner so as to ensure low sulfur content therein and maintain low temperature stability thereof.
U.S. Patent Application No. 20070049727, published Mar. 1, 2007 by Pollock et al., discloses low sulfur tall oil fatty acid compositions, as well as methods of using and making the same using distillation and adsorption, with the adsorbent disclosed as clay, acid-activated clay, silica, activated carbon containing compound, diatomaceous earth, or combinations and/or mixtures thereof.
WO Patent Application No. 2007/050030 describes how biodiesel fuel is produced from crude tall oil (CTO), by first heat-treating the CTO in order to remove the sulfur compounds and then mixing into the CTO C1-C8 alcohols, particularly methanol or ethanol, leaving the mixture to become at least partly esterified in a mixing tank reactor, followed by generating and then separating water and alcohol in a distillation column. Following these treatments, the alcohol and the water are distilled apart from each other and finally, an esterified fatty acid is removed by fractionation from the resin acids, in the third distillation column.
U.S. Application No. 20090217573, published Sep. 3, 2009, by Stigsson, discloses automotive fuels and fine chemicals from crude tall oil. The method for manufacturing fatty acid alkyl esters from tall oil comprises the steps of a) esterifying tall oil in at least one esterification reactor in the presence of an acidic catalyst and an C1 to C8 alcohol to form a crude product stream comprising fatty acid alkyl esters and water, b) separating water and alcohol from the crude product stream formed in step a) to form a dehydrated fatty acid alkyl ester product stream, and c) separating dehydrated fatty acid alkyl ester product stream from step b) into at least two product streams wherein one product stream is enriched in fatty acid alkyl esters and one product stream is enriched in resin acid compounds. There are disclosed fatty acid alkyl esters and resin acids manufactured by the method. Moreover there is disclosed a fuel composition and its use as an automotive fuel, said fuel composition comprises the fatty acid alkyl esters produced according to the present invention.
WO/2009/153408, published Dec. 23, 2009, by Saviainen, discloses methods and apparatus for producing motor fuel. Specifically, a method and an arrangement for maximizing the yield of fatty acids, which are associated with the process of the refining of tall oil and, at the same time, producing from them fatty acid esters, particularly methyl esters, for use as fuel. According to the present invention, crude tall oil is first treated with formic acid, with which the alcohol groups are esterified. After the separation of the pitch and resin, the crude fatty acids are esterified in a primary oil column of a refinery, where the water generated and the excess alcohol derived from the process of the esterification are removed by distillation. Generally, the fatty acids, which end up in the primary oil and the bottoms products, are also mainly esterified, according to the present method, and thus it is possible to maximize the amount of the fuel esters (FAME).
However, in spite of the above advancements, there exists a need in the art for a low sulfur fuel additive composition, and methods of making such composition.
There even also exists a need in the art for a low sulfur fuel additive that provides improved lubricity and low temperature properties to a fuel additive composition and also to the subsequent finished fuel.
There also exists a need in the art for a low sulfur fuel, and methods of making such fuel.
These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.